1. Field of the Invention
The present invention relates to a system for enabling connection among devices in a network.
2. Description of the Related Art
In a Fibre Channel Arbitrated Loop networks, devices are connected to one another to form a “loop” architecture, where all devices may communicate with any device in the loop. The connections are made with optical fibers or copper lines, which provide high bandwidth communication between the devices. Devices may be connected to the loop through two ports, where one port is used as a receiver and another as a transmitter. In such implementations, each fiber cable is attached to a transmitter of a port at one end and a receiver of another port at the other end. Alternatively, a single cable may be used for both receiving and transmitting data. In such case, the device need only have a single connection to another device in the loop. Devices connected in a Fibre Channel arbitrated loop may form a Storage Area Network (SAN), which may include numerous interconnected Fibre Channel Arbitrated Loops.
In one known architecture, a storage device drawer may include multiple hard disk drives and have two adaptor cards. Each adaptor card on the drawer may connect to an adaptor on a separate host system, where the fibre cable between each host and the drawer is bi-directional. Further, drawers may be daisy chained together, such that one host is connected to one storage drawer adaptor, and the other storage drawer adaptor is connected to an additional drawer. Any number of additional drawers may be daisy chained together, with the second host attached to the second adaptor of the last drawer in the daisy chain.
To add a drawer to the loop, if a drawer is connected to two separate hosts, then an administrator has to disconnect one host from one drawer adaptor, connect a cable between the new drawer and the drawer adaptor from which the host was disconnected, and then reconnect the host to the second adaptor on the new drawer. When the host is disconnected from the drawer, the Fibre Channel performs a loop initialization routine to configure the new arrangement. While the host remains disconnected, users can access data to the host remaining connected, but any users that accessed the loop through the disconnected host remain off-line and unable to access the data stored in the storage drawers. This downtime can be problematic, especially if the administrator takes a significant amount of time to connect the disconnected host to the new drawer.
Accordingly, there is a need in the art for improved techniques for adding devices to a loop.